Welcome to this lecture on Pulmonary Structures
This slide captures the learning objectives
that you should be able to answer
at the conclusion of this lecture.
First, describe the pleural membranes and
Describe the trachea, its wall composition
and bronchial branching pattern.
Compare and contrast the features of the right
and left lungs.
Describe the applied anatomy in performing
Describe the esophageal segments, constrictions
and the layers forming its wall.
Describe the locations of esophageal diverticula
and the relevance of Killian’s triangle.
And then we’ll summarize the key take-home
messages from this lecture.
Lastly, we’ll provide attribution for the
images that were used throughout this presentation.
Here is our body map and most of our attention
is going to be focused in the pleural cavities.
And then, we’ll also focus some of our attention
in the mediastinum
when we look at the esophagus and trachea, bronchi.
This particular slide represents the rationale
for talking about not only respiratory structures
such as the trachea, the bronchi and the lungs,
but also to include the esophagus.
What is interesting, developmentally, is that
the foregut derivatives will give rise not
only to GI structures, but will also give
rise to the pulmonary airways and the lungs.
So, if we take a look at this area here, we
are looking at the primitive foregut region
and here we see the development of the trachea
which then will lead to the development of
its branching pattern and then, more distally,
to the development of the lungs.
Here running posterior to the development
of the trachea would be the portion of the
foregut that will give rise to the esophagus,
the stomach and the proximal duodenum as well
as GI organs: the liver, its associated biliary
apparatus and then the pancreas.
This slide is demonstrating the concept of
the pleural membranes. Since the lungs reside
within their pleural cavities, we will have
investments of pleural membranes. So, we’ll
need to understand those membranes.
Here we’re looking at the right lung. Here
is the left lung. And then, lining the thoracic
cavity on either side, is this outer green
line. So, it’s just on the inner thoracic
wall. This is going to be your parietal pleura.
It similarly will be adhered to the inner
thoracic wall associated with the left pleural
cavity. If we follow this parietal pleural
membrane posteriorly, we will see that, at
the area where we have our vertebral column,
it will reflect back onto the surface of the
lung. This portion of the pleural membrane
that’s adherent to the surface of the lung
is now referred to as the visceral pleura.
There is a potential space between these two
pleural membranes and this potential space
represents the pleural cavity. In some cases,
excessive fluid, it may be blood or other
types of fluid that will excessively accumulate
within the pleural cavity converting the potential
space then into a fluid-occupied space.
This slide depicts the parietal pleural membrane
and its subdivisions. The subdivisions of
the parietal pleura are going to be named
according to the anatomic relationship of
each one. So, let’s take a look at those
Here, we can see the cut edge of the parietal
pleura associated with the right pleural cavity
and then over here we see the cut edge of
the parietal pleura that’s associated with
the left pleural cavity.
Most of the parietal pleura is going to have
a relationship to the vertebral column and
the rib cage. That then will be referred to
as the costovertebral pleura
or simply the costal pleura.
If we take a look, we also have the parietal
pleura that will cover the superior surface
of the left dome of the diaphragm along here
and then ascend up. Similarly, on the right
side, we have a portion of the parietal pleura
that’s associated with the right dome of
the diaphragm. This, then, is referred to
as the diaphragmatic pleura.
We will also have pleura that extends up and
over the apex of each lung up into the cervical
region, the inferior part of the neck. This
will be termed the cervical parietal pleura.
And then lastly, we’ll have parietal pleura
associated with each lung that will face the
mediastinum. And this would be referred to
as your mediastinal pleura.
When we think about the pleural membranes
and where they have points of reflection anatomically,
these points of reflection of the parietal
pleura will create various types of recesses
that are associated with the pleural cavities.
We have costal-diaphragmatic recesses associated
with the lungs, we have costal-mediastinal
recesses associated with each of the lungs
and we have vertebral mediastinal recesses
associated with the lungs.
The first two recesses are depicted, are illustrated
on this image. And so, the first one is a
fairly significant recess that projects inferiorly
and this is going to be the costodiaphragmatic recess.
Here we have the costal pleura and then, at
this point, it reflects onto the surface of
the diaphragm, becoming the diaphragmatic
pleura. And so, this area here is the costodiaphragmatic
recess. This represents a potential space
and may, in some cases, accumulate fluid.
We have the same costodiaphragmatic recess
that’s situated here on the left side as well.
The costomediastinal recess is along in through
here with the right lung.
We also have one on the left side.
This represents the point where the costoparietal
pleura is going to bend
and become the mediastinal parietal pleura.
The next slide will demonstrate the vertebral
mediastinal recesses. And that can be seen
along here. Again, the left side of the image
represents the right lung and here we have
the pleura reflecting in this area. This space
here is a potential space called the vertebral
mediastinal recess. And then we would have
a similar recess over here associated with
the other lung.
The next slide is going to demonstrate a procedure
called a thoracentesis. This type of procedure
is performed when there’s excessive fluid
accumulation in the pleural cavity. There
are several causes of excessive fluid accumulation.
The three primary causes would be heart failure,
lung infections as well as tumours.
When fluid becomes excessive, it has to be
removed from the pleural cavities and that’s
when a thoracentesis is performed. And then
let’s understand our applied anatomy to
be able to perform this procedure.
Here we’re in the mid-axillary line for
our point of reference. This happens to be
rib 9. This happens to be rib 10. So, we’re
operating within the 9th intercostal space.
Just inferior to rib 9, we have intercostal
structures, neurovascular structures, and
we want to avoid those so that we don’t
damage them. So, the best approach then is
to find the rib inferiorly here. And that
is going to be rib 10 and then to advance
the needle over its superior surface. And
you can see the tip of the needle has been
introduced into the costodiaphragmatic recess.
And then fluid can be removed once this needle
has entered that particular recess.